Mobile-phone use has increased dramatically in most countries since its introduction in the early to-mid 1980s. The expanding
use of this technology has been accompanied by concerns about health and safety. In the late 1990s, several expert groups
critically reviewed the evidence on health effects of low-level exposure to radiofrequency (RF) electromagnetic fields, and
recommended research into the possible adverse health effects of mobile telephone use.1–4 As a result, a number of studies have been conducted,5–14 including a large 13-country collaborative study, Interphone, with over 2700 glioma and 2400 meningioma cases and their matched
controls, which was recently published.15

Studies on the health effects of mobile phones are very complex, and interpretation of the results necessitates understanding
and careful consideration of various aspects including the timing of the study, the exposure variables of relevance and the
influence of methodological limitations. Indeed, the results of studies to date, in particular those of the recently published
Interphone international analyses,15 have been interpreted differently by various groups: some have taken them to suggest that mobile phones are safe, others
that they cause tumours, while some have suggested that the limitations of the studies were such that no conclusion could
be drawn.

This editorial discusses the main issues in the interpretation of the findings reported in recently published studies of brain
tumours in relation to mobile-phone use, particularly the largest of these, Interphone, and their potential public-health
implications.

Timing of the study

Most published studies to date have found no increased risk (and in many instances even a decreased risk) associated with
ever having used a mobile telephone. These studies, however, were conducted at a time when mobile communication was still
a relatively new phenomenon with low levels of use compared with today. As an illustration, though the largest study, Interphone,
started in 2000, …